Extension-ladder



(No Model.)

L. ,SWENSON EXTENSION LADDER. A

Patented Sept. (11,1883.

l 7V (i9. fi C INVBNOR.

' each section slide.

- UNITED 'STATES LoEEns swENsoN,

PATENT OEEICE.

or oEEsco, iowa.

EXTENSION-LADDER.

' SPECIFICATION forming part of Letters Patent No. 284,683, dated September 11, 1883.

Application filed May 26, 18H3.

sion ladder; and it consists in certain details.

of construction and arrangement of the several parts, as will be hereinafter more fully set forth in the specification, and pointed out in the accompanying drawings, in which- Figure l is a perspective view of the ladder raised or extended; Fig. 2, a front elevation of the same when the sections are in their closed position, Fig. 3, a detail perspective view of the pawl, ratchet-drum, and friction-clutch; Fig. 4, a detail rear elevation of the upper ends of the sections; and Fig. 5, a horizontal section of one of the lower frame-pieces, showing the tongued guide. A

The lower or ground section consists of the pivoted frames A B, pivotally secured to each other by the pivots m', which also form the.) ournals for the-pulleys m, said pulleys being secured in place and out of contact with frame B by the metallic bands n, which consist of three branches secured to frame A. The side pieces of the several sections are provided with grooves c c, in which the tongues on the end bars, k 7a', of A drum or pulley, Q, and a ratchet-drum and friction-clutch are attached to a shaft, I?, secured to fra-me A. Attached to each one of these pulleys is a cord or chain, Z, whichV passes over the pulleys m, and is secured at its opposite end to the cross-bar k. A cable or chain, g, is secured at one end to the rear upper cross-bar, k', of the frame A, thencepasses over a pulley, lz., secured to the upper rear cross-brace, f, ofthe section C, and thence down to the tongue-bar p of the upper section, D. This same arrangement of cords g and pulleys 7L will be carried out when additional sections are added. The ladder being in its closed position, as in Fig. 2, and it is desired to raise it, it is only necessary to throw out the frame B and then turn or wind the drums Q R through the intervention of shaft P and crank r. This winds up the cords (No model.)

Z on the aforesaid drums. At the same time the cables are drawing up the section C, as they are attached to the guide-bar K, the side tongues of the bar k sliding in the grooves a; but as the pulley h is attached to this section and the cord g is secured to the first and third sections, as shown in Figs. 1 and 2, it is evident that the sections C D must start to move at the same instant; but as the pulley h is secured to section C, the rate of movement of section D is double that of C, the movement, being like that of a differential pulley, so that the movable sections reach their limit of movement upward at the saine time-that is, the section D will, in raising, reach its highest point at the same time section Chas reached its highest point. As the sections are being raised any tendency to slip is prevented by the ratchet S engaging with the teeth on drum R. This ratchet is pivoted to frame A at t, and has one en d turned or bent outwardly and downwardly to actv as a friction-clutch when the pawl is raised from engagement with the ratchet-teeth. This bent end is grooved, so as to grasp the rim of the drum 011 the edge and sides, and thus obtain more friction. Vhen the sections are to be closed from their raised position, it is only necessary to raise the ratchet S, which throws the clutch S into action, the sections descending b v their own gravity, each section sliding within the next lower one.

A ladder constructed as described is very quickly and easily raised and lowered, and a steadiness of action assured not-heretofore acquired without complex mechanism.

I am aware that extension-ladders have been made with two or more grooved frames or panels, the panels sliding within each other, cords being attached from the several frames to the windlass of the winding mechanism, a collar being loosely placed 011 said windlass and turns with it, one set of panels being raised when the other is lowered, as in Patent No.

6,491. I am also aware that ladders with sliding sections, the sections sliding within each other, have been made, the tops of the sections having notched spring-catches attached thereto, which are thrown forward by coiled springs and catch any round that passes over them and retain the section at any height. I am also aware that ladders have been provided IOO with grooved sections for the reception of pins on the sections next above, the upper sections being provided with latches adapted to strike the under side of the rungs of the section when said section is being lowered, means being used to keep them out of the way when required. I am also aware that there are ladders with movable sections actuated by segmental gear through the intervention of shafts, the sections being provided with ropes running from each section to the winding-shaft. I am also aware that ladders have been constructed of sections moving within each other,

each upper section, at its top, having two pulleys connected by ropes to the sections above and below it, the extreme upper section havving a pulley with a rope passing through a guide on the lower sections, and adapted to be wound in opposite directions on the winding-shaft. Such forms of construction I do not claim; but

What I do claim isl. In an extension-ladder, the combination of a series of movable sections, each section being grooved internally to receive the sec tion next above it, and provided with a tonguebar to enter said grooves, a fixed section consisting of two frames, A B, pivotally secured to each other at the upper end by the pivots of two pulleys, with two winding-drums ser-YA cured to the exterior side of the rigid frame of the xed section, cables g Z, a friction-clutch, and ratchet mechanism, substantially as shown and described.

2. In an extension-ladder, the combination, with a fixed section and a series of movable sections having grooves and tongue-bars, as described, of cables g l, pulleys m h, pawl-andratchet mechanism, and friction-clutch s', arranged and acting substantially in the manner and for the purpose set forth. 

